Removing the Echo in a Presenter's Earpiece by Sonifex
23rd March 2015
Sonifex are showing the new Redbox RB-AEC Acoustic Echo Canceller on booth C2839 at this year's NAB .
The RB-AEC is a DSP based acoustic echo canceller primarily designed for the benefit of studio television and radio presenters. When a studio presenter's microphone signal is played out through a monitor speaker in the control room, it can be picked up by the control room microphone(s) and returned to the presenter's earpiece as an undesirable echo. In circumstances where green screen video processing is taking place, the delay can be greater than 200ms. Additionally, the dimensions, occupancy and distance between mouth and microphone can further influence the echo.
The RB-AEC is used to remove the entire control room monitor speaker output from the presenter's feed by adapting to the environment in which the control room microphones are placed. Although acoustic echo cancellation is more commonly implemented in telephony systems, the Sonifex RB-AEC is designed to produce broadcast quality cancellation.
Much like during a conference call configuration between two rooms, each room has a microphone and speaker to conduct a conversation. When an occupant of one room speaks, it takes a certain length of time before it is received in the second room. Without a suitable solution this 'delayed' signal can then be captured by the microphone in the second room and returned back to the first room as an echo.
In the particular example of TV production, as well as the processing/transmission delay, sound reflections from the control room monitor speaker into the control room microphone(s) cause the studio earpiece to suffer further delay. The sound reflections in the control room vary with the contents of the room, including any personnel present, and different frequencies produce varying reflections across various types of surfaces and magnitudes within the room.
The DSP solution offered by the RB-AEC can dynamically compensate for varying configurations.